XChat was previously my client of choice, although I don't have much of a need for IRC on a daily basis anymore. Specifically, HipChat's integration with KDE's system tray and general look and feel is much more polished, IMO.

I use bitlbee with hipchat so I can connect from Emacs. It's a bit awkward to set up, but it's a lot better than the official client since it works inside tmux+mosh.

Out of curiosity, what do you do with your IRC bots? I know HipChat can have bots, so I'd assume some similar functionality is possible. But Hipchat doesn't have decades of community developed bots, so IRC has a long head start.

I wrote a hosted bot service, to save you the hassle of maintaining one. Email me if you want to avoid the beta charge thing: https://www.getinstabot.com

HuBot and mmBot (a C#/.NET port) has an adapter for hipchat

And for Jabbr, which is a Jabber implementation on Signalr (a realtime thingy of .Net).

It's actually pretty neat, you can try it out on : https://jabbr.net (+ it's opensource if you want to implement your own team chat )